How to play 12 vs 24 Hour Challenge

Connect equivalent times through a clock conversion portal. Choose a difficulty and Learn or Challenge. Each round has ten missions. Learn gives hints and retries; Challenge scores the first submitted answer.

Practise at your own pace

Rounds are untimed by default. Optional Challenge timers count active answering time and pause on feedback screens or when you leave the tab. Review missed missions after your round.

Progress and privacy

Your current round and personal bests are saved on this device when browser storage is available. Use Clear saved progress to remove game progress from this device. No signup is needed.